The present invention relates to electronic circuits, and more particularly, to techniques for power management on integrated circuits.
Regulators with active filtration are commonly used on sensitive analog supply voltages. Regulators with active filtration enable multiple analog modules to share a common analog supply voltage without introducing noise to the supply voltage or picking up noise from the supply voltage.
In the Stratix® II GX field programmable gate array (FPGA) manufactured by Altera Corporation of San Jose, Calif., each transceiver channel, as well as each phase-locked loop, has an individual regulator. To provide headroom, each regulator operates from an elevated supply voltage, e.g., 3.3 volts.
In the Stratix® II GX, the 3.3 volt elevated supply voltage is shared among numerous analog circuits. Each analog circuit can be individually coupled to the supply voltage by closing a first switch that couples a gate of a transistor in an active regulator to the supply voltage, causing the transistor to turn on. When the transistor is on, current flows from the supply voltage to the analog circuit through the transistor. Each analog circuit can be individually decoupled from the supply voltage by opening the first switch and closing a second switch that couples the gate of the transistor in the active regulator circuit to ground.
However, the elevated supply voltage increases power consumption and requires the customer to supply a clear 3.3 volt power supply level, which is an added expense. This added expense can be a burden in a customer system that has a low data rate and that does not need to satisfy the high performance jitter requirements of 6 GHz transceiver. Therefore, it would be desirable to provide a system for managing supply voltages that provides more flexibility.